This invention relates to O-alkyl sulfonylisoureas having agricultural activity and in particular herbicidal activity.
U.S. applications Nos. 824,805, filed Aug. 15, 1977 now U.S. Pat. No. 4,127,405 and 840,389, filed Oct.6, 1977 now U.S. Pat. No. 4,169,719 disclose, inter alia, compounds of the following formula as herbicides: ##STR1## In the former, R is ##STR2## and in the latter, R is ##STR3## In each of those applications, R.sub.1 may be ##STR4## and R.sub.3, R.sub.4, R.sub.6 and R.sub.7 may each be hydrogen, fluorine, chlorine, bromine, or methyl. Moreover, in each application, each of R.sub.3, R.sub.6 and R.sub.7 may be methoxy, and R.sub.3 and R.sub.6 may additionally be nitro, trifluoromethyl or CH.sub.3 S(O).sub.n -, (where n=1 or 2). In each application, X may be methyl, methoxy, ethoxy or methoxymethyl, and Z may be methyl or methoxy.
U.S. Pat. No. 3,637,366 discloses compounds having the formula: ##STR5## wherein
R.sub.1 is hydrogen or lower saturated aliphatic acyl; and
R.sub.2 is hydrogen, 2-pyrimidinyl, pyridyl, amidino, acetyl or carbamoyl.
The disclosed compounds are said to provide control of crabgrass, cress, endive, clover and Poa annua.
Substituted pyrimidinyl sulfonylureas of the following formula, which are also para-substituted on the phenyl ring, are disclosed in Farmco Ed. Sci., 12, 586 (1957) [Chem. Ab., 53, 18052 g (1959)]: ##STR6## wherein R.dbd.H or CH.sub.3.
U.S. Pat. No. 3,823,007 discloses isourea salts as herbicides. ##STR7## wherein
R is chloro, bromo, iodo, cyano, alkyl, alkoxy, nitro, amino or ##STR8##
R.sup.3 is hydrogen or alkyl;
n is the integer one to three;
m is the integer one or two;
M is of alkali metal, alkaline earth metal or ammonium;
R.sup.1 and R.sup.2 are each independently hydrogen, alkyl, alkoxy, alkynyl, phenyl, substituted phenyl having a maximum of three substituents said substituents being alkyl, bromine, chlorine, alkoxy, phenoxy, mono and dihalogenated phenoxy, said halogen being chlorine or bromine, or the group ##STR9##
R.sup.4 and R.sup.5 are each independently hydrogen or alkyl.
U.S. Pat. No. 3,714,209 discloses the isopropylidineaminoethanol salt of p-nitrobenzenesulfonylisourea as a herbicide: ##STR10##
The presence of undesired vegetation causes substantial damage to useful crops, especially agricultural products that satisfy man's basic food needs, such as rice, corn, wheat, soybean and the like. The current population explosion and concomitant world food shortage demand improvements in the efficiency of producing these crops. Preventing or minimizing the loss of a portion of such valuable crops by killing or inhibiting the growth of undesired vegetation is one way of improving this efficiency.
A wide variety of materials useful for killing or inhibiting (controlling) the growth of undesired vegetation is available; such materials are commonly referred to as herbicides. The need exists, however, for still more effective herbicides that destroy or control weeds without causing significant damage to useful crops.